1. Field of the Invention
This invention relates to the casting of copper anodes for use in the electrolytic refining of impure copper and to the casting of refined copper.
2. Description of the Prior Art
Copper anodes used in electrolytic copper refining are normally cast in solid copper molds. In the past, common practice has been to treat the interior surfaces of such a mold before each metal pour with a slurry made up of a finely divided inorganic release material such as silica, suspended in a liquid medium, to prevent the molten metal from welding itself to the mold. The liquid medium is vaporized by the heat of the mold, resulting in deposition of the release material on the interior surfaces of the mold.
U.S. Pat. No. 2,050,375 discloses a copper release material comprised of a mixture of an inert substance selected from the group consisting of bone ash, bone black and graphite or combinations thereof and a suitable adhesive or binder such as rosin, copal, gum arabic, glue, gelatine and the like dissolved in a suitable liquid medium.
U.S. Pat. No. 3,126,294 discloses a copper release material comprised of aluminas which have been calcined at temperatures in the range of between 1800 degrees F. and 2200 degrees F. and dispersed in a liquid medium.
Also, U.S. Pat. No. 3,867,977 discloses copper release materials such as clay, ganister and lime which are dispersed in a liquid medium in addition to the materials previously identified.
Each of these release materials have been used with varying success by the copper refining industry. Recently however, new governmental safety regulations and environmental controls have caused a need for a new material to comply with these new regulations and still provide a mold release agent which is easily removed from the casting and which contains no impurities that will cause contamination or reduction in current efficiency of electrolytic copper refining cells.